In 1985, Vail Associates, Inc. (VA) contacted the United States Department of Agriculture – Forest Service (Forest Service) and proposed to develop the Category III (CAT III) and Tea Cup Bowl areas on the White River National Forest (WRNF) as part of the Vail Ski Area Master Development Plan (MDP). This 4,100 acre area is a currently undeveloped portion of VA’s existing Special Use Permit area. The Forest Service accepted the MDP after preparation of an Environmental Assessment (EA) and Decision Notice (DN) in 1986. However, the DN withheld approval of the development of the CAT III area pending the completion of a site specific Environmental Impact Statement (EIS). The final EIS was completed in August 1996.
Although VA’s proposal identified several development scenarios for the CAT III area, it focused on the one alternative in particular (the Proposed Alternative) which would add approximately 1,000 acres of lift-accessed ski terrain to the Vail Ski Area. Primary elements of the proposal included the construction of four ski lifts, ski trails, a skiway/road system, a restaurant, two warming shelters and food service facilities, ski patrol facilities, utilities, and three bridges spanning Two Elk Creek.
Although preliminary hydrologic modeling on the watersheds and sub-basins within the CAT III area was completed for the EIS using modeling software developed by the Hydrologic Engineering Center (HEC) of the U.S. Army Corps of Engineers (HEC-1), it is the intent of this term paper to investigate the effects that the development will have on the hydrologic system of the CAT III area using the HEC-HMS modeling software now available.
This term paper will focus on achieving the following objectives:
 | Identification of sub-basins within the Two Elk Creek watershed; |
| Identification of existing soil and native vegetation conditions; |
| Determination of the quantity and routing of exiting runoff resulting from a particular design storm; |
| The effects of this runoff on seasonal stream flow in Two Elk Creek at the CAT III area boundary; |
In order to achieve the objectives listed above, the following resources will be utilized:
| USGS 7.5’ Quadrangles for the CAT III area |
| Vegetation Maps |
| USDA Soils Maps |
| USGS Stream Gauge Data for Two Elk Creek |
| Precipitation Data for the Two Elk Creek watershed |
Other resources that have not been explicitly identified will be utilized to complete a study of the effects that different loss rates, routing methods, and transform parameters have on the runoff generated from the design storm.
The anticipated results of this study will determine the overall effects of the loss of vegetation due to development on the Two Elk Creek watershed, and will provide a comparison of these results (as obtained from HEC-HMS modeling) to the results presented in the EIS. In addition, I will become familiar with the desirable features and limitations of the HEC-HMS modeling software in preparation for future surface water modeling work.
